It was another night of poor shooting and mental mistakes mixed with a series of defensive breakdowns that allowed the hot-shooting Warriors to get countless open looks from the perimeter.

It seemed that the Celtics weren’t aware of Stephen Curry’s habit of pulling up and making 30-footers, because he was allowed to do so on three occasions. It also seemed they hadn’t scouted Klay Thompson, because they let him get to his favorite spot on the floor (baseline 3-pointer) with no resistance.

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And they definitely didn’t realize that David Lee (20 points) can shoot from the perimeter, because he was allowed 3 feet of open space each time he gathered the ball at the key. This loss was an example of lack of preparation, or lethargy without Rondo.

Paul Pierce, Jason Terry, and Jeff Green were a combined 12 for 50 from the field, with Pierce missing 16 shots in 20 attempts. The Celtics tried to make a run, scoring the last 8 points of the third quarter to slice the deficit to 76-67, but Jarrett Jack came off the bench to relieve Curry (22 points) and scored 6 of his 14 points during an 11-4 run to seal another win for the impressive Warriors.

The Celtics dropped to 5-10 on the road. Courtney Lee, who started in place of Rondo, led the Green with 18 points, but Pierce was limited to 13, and Kevin Garnett tallied just 6 in 24 minutes.

Pierce is growing impatient with the development of his team, especially after its 29-point loss to the Clippers.

The Celtics began their four-game trip with an impressive win on Christmas Day over the Nets, a team that had beaten them twice. But that victory was perhaps lessened by the fact that Brooklyn was struggling mightily, and fired coach Avery Johnson after losing by 15 points to Milwaukee the next night.

When the Celtics faced the league’s hottest team — the Clippers entered on a 14-game win streak — they wilted under the pressure, losing, 106-77.

“You can’t take nothing away from them, they’re a good team on a roll right now,” Pierce said of the Clippers. “But at the same time, if you look at the film, a lot of it was our coverage. A lot of it was our effort.”

Pierce said the Celtics consistency has to improve if they are going to be more than a .500 team.

“We’ve got to look at each other in the mirror,” he said. “It can’t be just one guy who yells every day, ‘Let’s go.’ It’s got to be everybody. You can’t have one guy or two guys or three guys going. It has to come from all five guys because when you have one guy off, it kills everything we’re trying to do.”

Pierce said he would hold off on calling a players-only meeting or sending a stronger message to his teammates.

“We’ve got to see how we end up on this trip and go from there,” he said. “We just got through playing well on Christmas and we take a step back, and we’ll see how the rest of this trip goes.”

Coach Doc Rivers also was disappointed in the performance against the Clippers.

“We didn’t play with great discipline, would be the word I would use,” he said. “I don’t know if it’s urgency or what­ever, but our discipline was horrible.

“Our problem all year has been the same problem. It’s not everybody, it’s two or three guys, and that’s all you need with this thing. And it’s not the same guys. That’s what’s been so frustrating about this season. I told our guys, and I have been very honest, ‘You are a .500 team right now.’ Until we prove we’re not, we are.”

Leandro Barbosa could return

The Celtics could get guard Leandro Barbosa back for Sunday night’s game. He has missed the last four games because of a personal matter. Barbosa was supposed to rejoin the team for Thursday night’s game, but his return was delayed . . . Avery Bradley is progressing as expected during his workouts in Waltham, Mass., and is projected to return Jan. 2. “Avery Bradley is going to be important to our team,” Rivers said. “He’s going to be one of those guys that changes your culture as far as on the floor and how he plays. I am hoping when he comes it helps one or two other guys do that.” . . . After blocking 23 shots in his previous two games, Fab Melo swatted just two in Maine’s 106-94 win Friday over Sioux Falls in the Development League . . . Pierce said he needed three stitches to close a cut in his mouth after a collision with the Clippers’ Chris Paul.

Gary Washburn can be reached at gwashburn@globe.com. Follow him on Twitter at @gwashNBAGlobe.

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